another tip for using self tappers (or drillers) is to be very careful once they start threading.
it is very easy to be pushing hard trying to get the hole to start ('just scratching the paint'), then it does start and before you know it the drill overpowers the screw and it strips the threads.
until you learn the 'feel', i would drill the small pilot hole, then install the screws.
a necessity for self tappers/drillers is a power drill/driver with adjustable clutch. start with it too 'soft' then adjust one click at a time til it seats the screw properly without stripping. even when seating screws by hand, it's easy to strip the threads. pretty fine line between snug, tight and 'oh crap!'
it is very easy to be pushing hard trying to get the hole to start ('just scratching the paint'), then it does start and before you know it the drill overpowers the screw and it strips the threads.
until you learn the 'feel', i would drill the small pilot hole, then install the screws.
a necessity for self tappers/drillers is a power drill/driver with adjustable clutch. start with it too 'soft' then adjust one click at a time til it seats the screw properly without stripping. even when seating screws by hand, it's easy to strip the threads. pretty fine line between snug, tight and 'oh crap!'